each ready to swing in on turn 3, each with a Howling Brave with 30+ attack. The only problem with this deck is that it can threshold screw you once or twice per run. I don't mind when this happens, however, since it doesn't affect your gold per minute earnings (it may actually increase them).

I see a couple of cards in your deck that could probably be reduced to 3x for more efficiency

I also wonder if Wild Growth is really needed here over some other utility

Think some troops are only there because there aren't alternatives who can fix thresholds, but I found the Wild Growths fairly key on my play-through (15/15 ) - only Prophet of the Sun grants crush, and Wild Growth is even better because the AI will chump block allowing an easy quick action win.

I see a couple of cards in your deck that could probably be reduced to 3x for more efficiency

I also wonder if Wild Growth is really needed here over some other utility

I just gave the set 4 cards another look, but I don't see anything that could make it into the deck.

Which cards can go down to 3? What would replace them?

And Wild Growth is simply there as the cheapest form of Crush. Before I put it in, too often you'd end up with a giant Coyotle who'd get chumped every turn. It also allows giant Ardent Recruiters to finish the game earlier.

I can come back once the full equipment list is revealed, but if you want something specific right now you can try:

-1 Whispering Breeze
+1 Righteous Paladin

I'm sure at least one set 4 card will make it, just not any spoiled currently.

I considered Paladin early on, but Whispering Breeze is easier to cast, more powerful in the short term, and a valid target for Dance of Dusk. I've haven't had an issue with Unique so far, but 1 Righteous Paladin isn't a bad change.

I've been trying it out with the substitution of Rhythmic Spiritualist (equipped) and Mesa Lookout (taking out Oakhenge Ceremony and Stargazer). The first gives you a spellshielded Coyotle (no Repel, Cory or Terrorantula problems if you have Dance of Dusk on it), and the other is lifegain, defense boost and quick, so you can drop it on the AI turn as a combat trick and then Dance of Dusk it on the next turn. The Mesa Lookout has nice synergy with the Ardent Recruiter, since you net +1 attack and +3 defense for 2 resources as a combat trick. And you get +2 health, which can trigger Ethereal Healers into play.

This makes the deck slightly slower in the event you have a Dance of Dusk in opening hand since you only have four 1-drop Coyotle instead of eight, but gives you a little more durability in the event you don't.

From running through the Arena several times, it seems the Dance of Dusk is nice when you get it, but as an Ethereal Healer deck it also does quite well without it.

I've been trying it out with the substitution of Rhythmic Spiritualist (equipped) and Mesa Lookout (taking out Oakhenge Ceremony and Stargazer). The first gives you a spellshielded Coyotle (no Repel, Cory or Terrorantula problems if you have Dance of Dusk on it), and the other is lifegain, defense boost and quick, so you can drop it on the AI turn as a combat trick and then Dance of Dusk it on the next turn. The Mesa Lookout has nice synergy with the Ardent Recruiter, since you net +1 attack and +3 defense for 2 resources as a combat trick. And you get +2 health, which can trigger Ethereal Healers into play.

This makes the deck slightly slower in the event you have a Dance of Dusk in opening hand since you only have four 1-drop Coyotle instead of eight, but gives you a little more durability in the event you don't.

From running through the Arena several times, it seems the Dance of Dusk is nice when you get it, but as an Ethereal Healer deck it also does quite well without it.

That's been my experience as well. Dance of Dusk just finishes games earlier and helps with the odd stalemate, but often the Ethereal Healers do most of the work.

I prefer more one-drop Coyotle because of their interaction with both Ardent Recruiter and Scrivener. Especially when Scrivener is out, the difference between having 2 troops to play on turns 2 and 3 and having only 1 is big.

Wild is finally getting a real spellshield troop next set, but Spiritualists can often be picked up for 31 plat (and can actually feel useful with their ability targeting ethereal healers) so it's very relevant

I put together my own deck fast. . .
It's mono diamond, but it might give you some queues about what you can test out within your own deck:

Plenty of overlooked cards / equipment / utility in there
Biggest one being Pawn which is actually BiS right now if you want to combo healer because it triggers on opponent's turn (and on your own healers entering play)